Sound reproduction system



March 25, 1969 E. L. SECHRIST SOUND REPRODUCTION SYSTEM Sheet Filed March 25, 1968 v INVENTOR.

0M/ARO A. 550/2? By .6 4 A'ITORNEYS March 25, 1969 E. 1.. SECHRIST 1 3,434,564

SOUND REPRODUCTION SYSTEM 7 Filed March 25, 1968 INVENTOR.

fw/meo Z, 550/057- March 25, 1969 E. L. SECHRIST 3,434,564

SOUND REPRODUCTION SYSTEM Filed March 25, 1968 Sheet 3 of 3 INVENTOR. fan/.420 Z EC/Vk/5T a d ATTORNEYS United States Patent US. Cl. 18131 6 Claims ABSTRACT OF THE DISCLOSURE A sound reproduction system having a housing with a lateral slot in one face thereof near the top, the housing enclosing a plurality of moving cone speakers, one of which projects sound waves through the front of the housing near the bottom thereof, and the other of which faces upwardly and projects sound waves toward the top of the housing from the bottom thereof, a plurality of resonance chambers located within the housing, one of which is positioned above the front sound projecting speaker between the speaker and the slot and the other of which is positioned above the upwardly facing speaker and contains a plurality of individual resonance chambers, each of which differs in size from the other.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to sound reproduction systems and more particularly to a resonance apparatus to be used in connection with sound reproduction systems.

Prior art Sound reproduction systems used in modern hi-fidelity and stereophonic installations emphasize the ability of the system as a whole to reproduce sound over the entire frequency range audible to the human ear. Although the pure sounds produced by the human voice and most musical instruments can be reproduced with relatively inexpensive moving cone speakers, the harmonics of the pure tones which add greatly to the quality and timbre of the sound are difiicult to reproduce. Therefore, it has become customary to utilize multi-speaker arrangements in sound reproduction systems. In such systems the various speakers are designed to reproduce sound in different frequency ranges. For instance, a full-range speaker system may require three or more separate speakers, one of which is designed primarily to reproduce low-frequency sounds, another to reproduce high-frequency sounds, and a third to reproduce mid-range frequency sounds. Such specialty speakers are expensive and increase the size of the resultant system.

It is also known to the prior art to accentuate the speakers abilities by enclosing them in a cabinet or housing containing a bafile arrangement which enhances the tonal quality of the speaker. However, such prior art baflies are relatively large or are of limited range.

SUMMARY My invention pertains to a sound-reproduction system which incorporates in a housing, one or more moving cone speakers, which may be of the multi-frequency range type, and a reverberation type bafiie arrangement. The novelty of my invention lies in the design and placement of the non-speaker components of the system in combination with a particular speaker positioning.

In a preferred embodiment, my sound reproduction system utilizes a wooden cabinet or housing having relatively thick top, bottom and side walls and relatively thinner front and back walls. Two moving cone speakers which may be of a multi-range coaxial cone or two-way or three-way type or which may be of types differing from "ice each other, are positioned interiorly of the cabinet. One of the speakers is attached to the interior of the front wall directly behind an aperture therethrough. This speaker projects through the front wall. Directly above this speaker, the first of my bafile chamber reverberation devices is positioned. The other speaker is mounted in the housing in such a manner that it projects sound upwardly interior of the housing. Directly above this speaker, the second of my bafile chamber reverberation devices is positioned. The top of the front wall has a longitudinal slot thereacross above the two baffle devices. The remainder of the interior of the housing may be filled with sound insulation or may be equipped with prior art type baflle arrangements.

The first of my bafile chamber reverberation devices consists of a series of closely spaced apart sheets of material defining chambers therebetween. The side edges of the sheets of material are connected together by spacing members which define the outer edges of the chambers. Each of the chambers is divided into two sub-chambers by a longitudinal dividing wall. No two of the sub-chambers is of the same size. This first bafiie chamber device is basically described in my US. Patent No. 3,160,225.

The second baifie chamber device consists of a series of elongated resonance chambers arranged in rows such that the chambers in each row are of the same depth but of differing widths and heights. The device is mounted so that sound waves coming from the speaker are transmitted through the length of the chambers. In this manner resonance harmonics are created from the original speaker sound to add timbre and quality.

It is then an object of this invention to provide an improved sound reproduction system having resonance chambers therein.

It is another object of this invention to provide a sound reproduction system providing extended frequency range sound from limited range moving cone speakers by directing the sound from the speakers through a resonance chamber.

Other and further objects of this invention will be apparent to those skilled in this art from the following detailed description of the annexed sheets of drawings which, by way of a preferred embodiment of the invention, illustrate one example of the invention.

BRIEF DESCRIPTION OF DRAWINGS FIGURE 1 is a rear plan view of a speaker cabinet utilizing the principles of the invention with the rear wall of the cabinet removed.

FIGURE 2 is a perspective view of one of the resonance chamber assemblies of this invention.

FIGURE 3 is a fragmentary cross-sectional view of the cabinet of FIGURE 1 illustrating another of the resonance chambers of this invention.

FIGURE 4 is a fragmentar cross-sectional top view of the cabinet of FIGURE 1, illustrating the two resonance chambers.

FIGURE 5 is a plan view of another embodiment of a resonance chamber according to this invention.

FIGURE 6 is a front plan view of the speaker cabinet of FIGURE 1 with portions broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGURE 6 illustrates a loudspeaker cabinet 10 having a top 11, a bottom 12 and side walls 13 and 14. The' 3 the front of the cabinet above the top 19 of the front wall 17 and below the bottom 20 of the top 11 of the cabinet.

In the preferred embodiment, the cabinet 10 has a back wall which may be removed for access to the interior thereof. FIGURE 1 illustrates the interior of the cabinet 10 as seen through the removal back wall. Two moving cone speakers 21 and 22 are positioned interiorly of the cabinet 10. The speaker 22 is mounted on the inside face of the front wall 17 directly behind a circular opening therein. The speaker 22 may be mounted by any conventional-means such as screws 23. The speaker 21 is suspended in the cabinet 10 and mounted on mounting blocks 24 which bottom on the inner surface 25 of the bottom 12 of the cabinet. The speaker 21 is mounted so that its cone projects sound upwardly within the interior of the cabinet. The cone of the speaker 2 2 projects sound primarily through the opening in the front 17 of the cabinet.

Two reverberation chambers 26 and 27 are positioned interiorly of the cabinet. The chamber 26 is attached to the inside face of the front wall 17 above the speaker 22 and below the slot 18. Preferably, the top of the chamber 26 is aligned with the bottom of the slot 18. The chamber 27 is also attached to the inside face of the front wall 17 and is positioned above the speaker 21 and below the slot 18. As with the chamber 26, preferably the top of the chamber 27 is aligned with the bottom of the slot 18. Although FIGURE 1 illustrates the width of the chamber 27 as being less than the width of the cone opening of the speaker 21, it is to be understood that both the chambers 26 and 27 may have dimensions which are greater or less than are illustrated.

FIGURE 2 is a perspective view illustrating the sound chamber 27. The chamber consists primarily of a plurality of individual rectangular cross section elongated sub-chambers. The sub-chambers are of varying sizes in terms of depth, width and height. In the preferred embodiment illustrated, the chamber 27 is constructed of a plurality of sheets of wood 30 all of which have the same width. The top edges of the sheets 30 are stepped as at 31. The steps may be the same for adjacent sheets 30 as is illustrated by the sheets 30a and 3% or the steps may be different as is illustrated by the difference between the steps in sheets 30b and 30c. Additionally, the sheets may be of differing heights as is illustrated by the sheets 30b and 30c. Adjacent sheets are joined together by wooded strips 32 of varying lengths, but of the same width. The strips 32 are attached to the sheets as by glueing or the like at the area of the steps. The strips 32 have lengths equal to one of the adjacent sheets 30 at the step. In this manner, rows of sub-chambers are formed. Each row differs in depth from the others and, due to the step ping of the sheets, each of the sub-chambers is of a different size.

The sound chamber 26 is constructed of a plurality of tapered wood sheets 33 which are spaced apart at their outer side edges by wooden strips 24. The sheets 33 are spaced apart a distance which is substantially smaller than the width of any of the individual rows of sub-chambers in the sound chamber 27. There is thus created a plurality of tapered thin chambers in the sound chamber 26. As is best shown in FIGURE 4, each of these chambers 35 is divided into two sub-chambers by longitudinal strips 36. The strips 36 are offset from each other so as to provide sub-chambers of differing sizes. As is shown in FIGURE 3, some of the chambers 35 can be offset by stepping the sheets 33.

In order to increase the difference in the effect on the sound waves being transmitted through the sound chambers which is encountered in the individual sub-chambers, the sheets 30 defining the rows of sub-chambers in the sound chamber 27 can be made double for one or more rows as is illustrated at 38 in FIGURE 4. Additionally,

4 the same doubling of sheets can be used with the sound chamber 26 as is illustrated at 39 of FIGURE 4.

Therefore, because of the placing of the sound chambers 26 and 27, sound waves originating from the speaker 21 are directed upwardly through the individual subchambers of the sound chamber 27 where the primary wave is broken up into a plurality of individual waves each in a sub-chamber. The sub-chambers aid in increasing the tonal quality of the sound wave through reverberation and harmonic effects. Because of the different sizes and lengths of the sub-chambers, each chamber has a different effect on the primary sound wave.

Sound chamber 26 additionally effects the sound waves passing through it both from the speaker 22 as well as secondarily from the speaker 21. After the sound waves have passed through the sound chambers 26 and 37 they exit through the front of the cabinet 10 by means of the shot 18.

FIGURE 5 illustrates a second embodiment of the sound chamber 27. In this embodiment, the sheets which define the rows of sub-chambers are stepped at both the top and the bottom edges. In this way, not only do the sound waves exit from the top of the sound chamber at differing points, but they also enter the bottoms of the individual sound chambers at differing points, thereby increasing the difference in effect imparted to each sound wave by the differing sub-chambers.

It can therefore be seen from the above, that my invention provides for a novel sound reproduction system having increased tonal qualities resulting from the combination of specific speaker positioning and the use of nonspeaker sound chamber components.

I claim as my invention:

1. In a sound reproduction system; the improvement of a sound chamber having a plurality of individual rectangular cross section sub-chambers arranged in rows, the sub-chambers in each row having the same depth but different widths and heights, the sub-chambers in different rows having sizes differing from sub-chambers in other rows, and the sound chamber positioned in spaced relation to the cone opening of a moving cone speaker.

2. A sound reproduction system comprising a closed housing having a front wall, a plurality of sound reproduction speakers within said housing, an opening through said front wall, one of said speakers mounted adjacent said opening to project sound therethrough, another of said speakers mounted interiorly of said housing to project sound upward-1y within the interior of said housing, sound resonance chambers mounted on said front wall interiorly of said housing, one of said chambers having a plurality of elongated open-ended sub-chambers of differing sizes, said one of said chambers positioned to receive sound waves projected from said upwardly projecting speaker through one end of said sub-chambers, and a sound transmitting slot through said front wall above said resonance chambers.

3. A sound reproduction system comprising: a hollow cabinet having a front wall with an aperture therethnough in the lower portion thereof, a first speaker mounted in said housing over the said aperture and positioned to project sound through the aperture, a second speaker mounted in said cabinet and adapted to project sound upwardly interiorly of said cabinet, a first sound chamber mounted in said cabinet above said first speaker, a second sound chamber mounted in said cabinet above said second speaker, an elongated sound transmitting slot through said front wall above said sound chambers, said first sound chamber having a plurality of spaced-apart relatively thin wood sheets, said sheets being narrower at the bottom than at the top, said sheets being attached together at the side edges thereof by spacing blocks having widths thicker than the widths of said cheets thereby defining sub-chambers between the individual sheets, said subchambers divided by vertical wooden strips, said strips offset from one another, said second sound chamber having a plurality of elongated rectangular cross section subchambers of diifering sizes open at each end thereof arranged in rows, the sub-chambers in each row having the same depth but differing widths and heights, and whereby the said sub-chambers are adapted to receive sound waves from the said second speaker through an opened end position above said second speaker.

4. A sound reproduction unit comprising: a housing having top, bottom, front, rear and side walls and having an aperture formed within the said front wall, a first speaker mounted on said front wall over said aperture and within said housing whereby to project sound waves through said aperture, a second speaker mounted on said base within said housing and facing upwardly whereby to project sound waves toward the top of said housing, an elongated slot formed within and extending across said front wall adjacent the upper end thereof, and a.

sound resonator block positioned within said housing over each said speaker and having closed side walls, an open base positioned in juxtaposition to each said speaker, an open top positioned in juxtaposition to said elongated slot, said resonator block comprising a series of thin vertically extending walls and a plurality of upstanding spacers interconnecting said walls to define a plurality of reverberation tubes, wherein the length of various walls and spacers and the relative spacing of said spacers from one another are such that the configuration and lengths of said tubes differ from one another.

5. A sound reproduction unit according to claim I wherein the bases of said tubes terminate at different relative distances from said speaker.

6. The sound reproduction unit according to claim 4 wherein a plurality of said resonator blocks are positioned within said housing and the bases and tops of the tubes of at least one of said blocks terminate in planes differing from one another.

References Cited UNITED STATES PATENTS 1,969,704 8/1934 DAlton 181-31 1,98 1 ,9 62 11/193 t Marriott 18'13 1 2,880,817 4/1959 Burns et a1 18 1-31 3,160,225 12/ 1964 Sechrist 181-31 FOREIGN PATENTS 1,216,851 11/1959 France.

STEPHEN J. TOMSKY, Primary Examiner. 

